1. Technical Field
The present invention relates to a machining method of an optical fiber base material.
2. Related Art
An optical fiber base material undergoes a primary elongation with heating and elongation and diameter reduction, using an elongation apparatus that includes an electric furnace, and is machined to have a suitable diameter for a drawing machine. Also, spindle shapes suitable for drawing at both ends or one end of the optical fiber base material are formed by the drawing using a glass lathe. Further, the optical fiber base material is hung by the drawing machine via a dummy glass rod fused to one end of the optical fiber base material, and the optical fiber is drawn forth from a thin diameter portion having the spindle shape at the other end of the optical fiber base material.
An optical fiber base material drawing includes heating, by a burner flame, the optical fiber base material horizontally gripped by a chuck of a glass lathe, moving a tail stock of the glass lathe while adjusting the fire power, and drawing the base material. As a result, the softened part of the optical fiber base material becomes thinner gradually, and then the spindle shape is formed. Finally, the optical fiber base material is thermally cut by adjusting the flame smaller and heating locally, and the spindle-shaped parts are ends of the optical fiber base material.
Also, when drawing the optical fiber from the optical fiber base material, if there are scratches or impurities on the surface of the optical fiber base material, they will be the reasons such as a disconnection of the drawn optical fibers, changes of characteristics and the like.
Here, the surface of the optical fiber base material is finished in a smooth state without impurities by a flame polishing.